1. Field Of The Invention
The present invention relates generally to self-processing cameras. In the use of such a camera a film cartridge containing a plurality of film units is inserted into the camera. After exposure of a film unit in the camera, the film unit is transported between the nip of a pair of pressure rollers to release processing solution stored with such film unit and deposit the solution uniformly over the surface of the exposed area of the film unit. To automate the processing of the exposed film unit, the camera may include a battery-powered motor that is used in combination with suitable gearing to drive the pressure rollers and to actuate a picker device to feed the film unit into the roller nip. In such a camera it is important that the pressure rollers rotate through a sufficient number of revolutions to ensure uniform processing of the film unit. It is therefore desirable to provide in a camera means which ensures that a sufficient number of revolutions of the pressure rollers in a given time will be effected in transporting each film unit to thereby permit proper processing of the film unit.
2. Description Relative To The Prior Art
From U.S. Pat. No. 3,641,412 it is known that the amount of paper dispensed from a motor-assisted paper-dispensing apparatus may be controlled by an arrangement that includes a gear, having electrically conductive and nonconductive portions, and a stationary electrical contact that wipes against such gear to thereby determine whether or not current from a battery will be delivered to the motor via an electric circuit that includes the gear and the contact. When the apparatus is not in use the gear is at rest and the electrical contact is engaged with the insulated portion of the gear. To initiate the dispensing of paper from this apparatus, the patent suggests that a parallel electric circuit be provided between the motor and the battery to commence rotation of the gear drive to the paper feed and to thereby also rotate the gear which is mechanically coupled to this gear drive. The parallel circuit is effected by depressing a button on the apparatus, which causes the closing of secondary electrical contacts during the period for which the button is depressed. The button, however, must be depressed for a time sufficient to enable the gear to be rotated at least through a sufficient extent to permit the stationary contact to engage the conductive portion of the gear. While the apparatus described in the prior art may be suitable for a paper dispenser it is not particularly suitable for use in an automatic self-processing camera. It is preferred in such a camera to have movement of the shutter release initiate exposure, processing and removal of the film unit from the camera. It would be undesirable in such a camera to require that the photographer maintain pressure upon the shutter release member for any time greater than the very minimum needed to trip the shutter.
It is an object of the invention to provide in a self-processing camera improved means for controlling the drive to a pressure roller which means controls the number of revolutions of the pressure roller when effecting processing of an exposed film unit.
It is a further object of the invention to provide in a self-processing camera an improved means for controlling the drive to a pressure roller which means is actuatable after exposure of a film unit without the need for the photographer to maintain pressure on the shutter release button for any length of time greater than that needed to expose the film unit.
Briefly, the foregoing and other objects are accomplished by providing in a self-processing camera, which includes an electric motor and a drive which couples the motor to a pressure roller, an improved control for controlling electric current to the motor, which control includes a rotatable star wheel that is rotated incrementally through a cycle so that one complete revolution of the star wheel is associated with a desired number of rotations of the processing roller. The angular orientation of the star wheel relative to electrical contacts determines whether or not current will be furnished to the motor. In order to automatically commence cycling of the star wheel and therefore the furnishing of electric current to the motor the improved control means further includes a means for mechanically nudging the star wheel from an end-of-cycle position in which no current is furnished to the motor to an angular orientation in which electric current may be furnished to the motor. The star wheel nudging means is made cooperable with the camera's shutter release member so that the star wheel is nudged after exposure of the film unit and with the return of the shutter release member to a retracted position.
As used herein the term "star wheel" refers to a rotatable member which includes a plurality of teeth or other projections located radially about the center of rotation of the member and which teeth or projections are adapted to be periodically struck by an element or elements associated with the drive of the camera's motor to thereby rotate the star wheel through a cycle. Contrary to the teachings of U.S. Pat. No. 3,641,412 the star wheel in accordance with the invention described herein is not rigidly coupled to a motor drive. Rather, the star wheel is permitted to have s significant play in angular orientation to enable it to be mechanically nudged from its end-of-cycle orientation.
Various means for practicing the invention and other advantages and novel features thereof will be apparent from the detailed description of the preferred embodiment of the invention presented below.